I. Field of the Invention
The present invention relates generally to spacer devices used in conjunction with reinforcement structures for large concrete articles such as pipes, boxes and building structures. More particularly, the concept as related to spacers for use in maintaining concentric or parallel reinforcing assemblies in spaced relation relative to each other and to a form or mold in the fabrication of concrete structures.
II. Related Art
The manufacture of reinforced concrete structures often involves the use of a pair of steel mesh fabric shapes disposed in spaced parallel relation within the structure and spaced from the surfaces of the structure. In boxes, tanks, pipes or other enclosed structures, may resemble concentric mesh fabric cages and may be round, square, rectangular or other enclosing shape or even as sections of flat mesh for use in concrete walls. These reinforcing structures are typically welded wire or reinforcing rod (rebar) mesh fabric assemblies that may be characterized by a relatively dense lattice-weaving pattern which leaves relatively small openings through which the assemblies must be tied together in fixed relation by spacer elements to maintain the desired fixed space orientation both between the mesh structures and between the mesh structures and any molds for the casting or other pour operation. During the manufacturing process, particularly with precast shapes, various forces may be exerted on the double reinforcing mesh structures such as cage structures that may tend to separate the fabrics or tend to move them closer together. Twisting forces may also occur so that the spacers must be adequately secured to both fabrics, cages, etc. Pouring steps may be particularly stressful to the framework.
It is known to provide formed bent wire spacer elements to space a pair of wire reinforcing fabrics and to engage a form at one edge. These devices have been assembled and secured in place using wire ties or by being welded in place. More recently, spacer devices have been developed which can be manipulated into place without the use of ties or welds. Such devices are disclosed in Tolliver (U.S. Pat. No. 4,489,528) and Schmidgall et al (U.S. Pat. No. 4,999,965), for example. While these devices do space fabrics from each other and from mold walls, they require sections of wire or rods to be formed in intricate patterns that must be manipulated into place to attach to the mesh fabrics and that remains quite a labor-intensive assembly operation, even though welding or ties may not be necessary.
Thus, there remains a need for a spacer device for spacing, positioning and securing of spaced pairs of metal or other reinforcing fabric shapes in concrete structures that enables a less labor-intensive assembly and which enables the spacer devices themselves to be more easily fabricated from a variety of materials.